Electrophotographic copying apparatus

ABSTRACT

A compact and light-weight electrophotographic copying apparatus which includes an original feeding table and a photosensitive paper supply table both disposed within a machine housing in the upper portion thereof, means for transporting an original toward an original illuminating station, means for feeding sheets of photosensitive paper from said paper supply table in synchronism with the movement of the original and transporting the sheets to an exposure station optically connected to said illuminating station through an optical system, whereby the original is electrophotographically copied on the sheets of photosensitive paper in succession without any trouble or malfunctioning during operation.

United States Patent Komori et a].

[ ELECTROPHOTOGRAPHIC COPYING APPARATUS [75] lnventors: ShigehiroKomori, Yokohama; Jiro Sato, Kawasaki; Kazumi Umezawa, Yokohama, all ofJapan [73] Assignee: Canon Kabushiki Kaisha, Tokyo,

Japan [22] Filed: Nov. 5, 1970 [21] Appl. No.: 87,098

[30] Foreign Application Priority Data [451 July 3,1973

Primary Examiner-Samuel S. Matthews Assistant Examiner-Russell E. Adams,Jr. Attorne'y-Ward, McElhannon, Brooks & Fitzpatrick [5 7] ABSTRACT Acompact and light-weight electrophotographic copying apparatus whichincludes an original feeding table and a photosensitive paper supplytable both disposed within a machine housing in the upper portionthereof, means for transporting an original toward an originalilluminating station, means for feeding sheets of photosensitive paperfrom said paper supply table in synchronism with the movement of theoriginal and transporting the sheets to an exposure station opticallyconnected to said illuminating station through an optical system,whereby the original is electrophotographically copied on the sheets ofphotosensitive paper in succession without any trouble or malfunctioningduring operation.

2 Claims, 16 Drawing Figures 1 ELECTROPHOTOGRAPHKC COPYING APPARATUSBACKGROUND OF THE INVENTION Field of the Invention This inventionrelates to an electrophotographic copying apparatus of the type in whichcopying paper sheets fed one by one are subjected to through-slitexposure process while an original to be copied is being transported,and more particularly to improvements in means for feeding copying papersheets and means for transporting the original which are incorporated insuch a copying apparatus.

Description of the Prior Art In any known electrophotographic copyingapparatus of the described type, it has often been the practice that anoriginal to be copied is transported along a curvilinear path and thatthe original must be only in the form of thin sheet and any thickeroriginal cannot be copied. If the original to be copied has asubstantial thickness, such original may strike the original transportmeans and thereby be deformed or jammed in the course of transport.Another disadvantage of the known apparatus is that the location of acopying paper supply table in a relatively lower portion of the machinehousing has led to difficulties in supplying the copying paper sheets.Furthermore, even in a copying apparatus equipped with means forpreventing sheets of photosensitive paper from being supplied inoverlapping relationship, such means may fail to ensure reliableperformance and sheets of photosensitive paper may be fed in overlappingrelationship to cause jamming or other trouble during the course offeed.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide an improved electrophotographic copying apparatus which canovercome the above-described disadvantages and which has high practicalvalues such as compact and lightweight construction and greatconvenience in operation, especially in feeding photosensitive sheets.

It is another object of the present invention to provide anelectrophotographic copying apparatus in whicha horizontal path oftransport is provided for an original to be copied so as to enable anythick original to be readily copied.

It is still another object of the present invention to provide means forpreventing an original from striking original transport means with toogreat an impact which may cause deformation or deviation of the originalbeing transported, and ensuring the original to be transported at apredetermined velocity while synchronizing the feed of photosensitivesheets with the transportation of the original.

According to a feature of the present invention, an original feedingtable and a photosensitive sheet supply table are disposed within amachine housing in the upper portion thereof. An original resting on theoriginal feeding table is horizontally fed toward an originalilluminating station, and in synchronism therewith a photosensitivesheet is horizontally fed from the photosensitive sheet supply table inthe opposite direction to the direction of movement of the original. Thephotosensitive sheet thus fed is passed through electrically chargingmeans and through-slit exposure means both disposed vertically along oneend wall of the machine housing, so as to form an electrostatic latentimage of the original on the photosensitive sheet.

According to a further feature of the present invention, the originalfeeding table is mounted on the machine housing for pivotal movementwith respect thereto, and original transport means including an originalilluminating station is disposed in front of the original feeding tableand supported openably or detachably with respect to the machinehousing.

According to a further feature of the present invention, the distanceover which the original placed in the housing travels to reach theoriginal illuminating station differs from the distance over which thephotosensitive sheet fed from the supply table travels to reach theexposure means, while the original and the photosensitive sheet aresychronized together in movement during the initial stage of a copyingoperation, thus minimizing the space occupied and making the entireapparatus compact in structure.

According to still a further feature of the present invention,photosensitive sheets are fed intermittently one by one and these fedphotosensitive sheets are initially in a certain degree of overlappingrelationship with one another, whereafter such overlapping sheets arespaced apart axially thereof by providing a difference between therotational velocities of paper feed roller and paper transport rollersboth controlled by a paper feed drive motor. The leading edge of eachphotosensitive sheet thus separated actuates a microswitch disposed inthe path of photosensitive paper, thereby stopping the paper feed drivemotor. Thus, it is prevented by a simple mechanism that all thephotosensitive sheets on the supply table are fed continuously inresponse to a single copy-start signal until the paper stock exhausts onthe supply table.

The above and other objects and features of the present invention willbecome more apparent from the following detailed description of variousembodiments of the invention when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of anelectrophotographic copying apparatus according to an embodiment of thepresent invention.

FIG. 2 is a longitudinal cross-sectional view of the same apparatus.

FIG. 3 is a horizontal cross-sectional view of the same apparatus.

FIG. 4 is a schematic view showing the drive system in the apparatus ofFIG. 1.

FIG. 5 is a fragmentary front view, partly in cross section, of thephotosensitive paper transport roller having a one-way transmissionclutch mechanism in the same apparatus.

FIG. 6 is a sectional view taken along lines 6-6 of FIG. 5.

FIG. 7 shows in perspective view an example of the paper feeding meansaccording to the present invention.

FIG. 8 is a front view of the paper feeding means shown in FIG. 7.

FIG. 9 is a longitudinal cross-sectional view of one end portion of thepaper feed rollers.

FIGS. 10 and 11 are front views of the idle mechanism in the paperfeeding means.

FIG. 12 is an enlarged plan view showing one half of the originaltransport means according to the present invention.

FIG. 13 is a view taken along lines 1313 of FIG. 12.

FIG. 14 is a view taken along lines 14-14 of FIG. 12.

FIG. 15 is a perspective view showing the original transport means ofFIG. 12 with the upper roller group supporting unit for the originaltransport means being opened.

FIG. 16 illustrates the manner in which the transport rollers and guideplates are operated in the original transport means of FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, theelectrophotographic copying apparatus embodying the present inventionincludes a machine housing 1, and an original feeding table 3horizontally disposed in the housing 1 at the upperportion thereof. Theoriginal feeding table 3 is pivotally mounted on the housing 1 by meansof a shaft 2. The copying apparatus further includes original transportmeans 5 detachably hinged at 6 to the housing 1 for pivotal movementabout a shaft 6,. The original transport means is normally maintained ina horizontal plane common to the plane of the original feeding table 3.An original resting on the original feeding table 3 is fed therefromalong a guide member 3, provided on one side of the original transportmeans 5 and transported horizontally by four sets of transport rollers8-11 and guide plate 12 in the original transport means 5 so as to passthrough an original illuminating station comprising a guide plate 13 anda glass sheet 14. Thereafter, the original is discharged along a guideplate 15 onto an original receiving tray 16.

When the original is passing through the illuminating station, thesurface thereof carrying thereon an image to be copied is exposed tolight from a light source 17 with a reflector 17 so that the image onthe original is projected through an L-shaped optical system comprisinga mirror 19 and a lens L onto a sheet of photosensitive paper P(hereinafter referred to as paper sheet P) which is passing through anexposure station as will be described later. A blower 20 is provided atthe entrance of a blast duct, and a photosensitive paper supply table 21is disposed below the original feeding table 3. Paper sheets P piled onthe photosensitive paper supply table 21 are one by one fed by a paperfeed roller 22 and further guided downwardly by three pairs of papertransport rollers 23-25 and guide plate 26 into electrically chargingmeans 27 and exposure means 28. Liquid-type developing means 29 isprovided at the bottom of the housing 1 below the optical system so asto develop the paper sheet P transported thereinto by rollers and guidedalong guide plate 30.

The paper sheet thus developed is squeezed by a pair of squeeze rollers31 to remove the residual developer on the paper sheet, which isthereafter passed to drier means 32. The drier means 32, which issupplied with warm air sucked from the illuminating station by theblower 20 and heated by a heater 33 disposed within the duct, blows suchwarm air against the paper sheet discharged thereinto from thedeveloping means 29 so as to dry the wet paper sheet and fix an imageformed thereon. Thereafter, the paper sheet P is passed throughdischarge rollers 34 onto a copy tray 35.

Drive mechanism for the photosensitive paper transport rollers 23-25 anddrive mechanism for the original transport rollers 8-11 are operativelyassociated together so that the passage of the original through theoriginal transport means 5 and the passage of the photosensitive paperthrough the electrically charging means and exposure means 27 and 28 aresynchronized with each other. These drive mechanisms are integrated intoa unitary drive system as shown in FIG. 4. A motor 36 is started byclosing a power switch (not shown) to drive a gear 37, which in turndrives, via chain 38, two pairs of photosensitive paper transportrollers 24 and 25, a pair of squeeze rollers 31 and a pair ofphotosensitive paper discharge rollers 34. At the same time, four setsof original transport rollers 8-11 are also driven by the gear 37 viaanother transmission provided by chain 38, gear 39, or roller 39connected to chain 38, gear 40 connected to the gear 39,, and otherintermediate gears 41-43 (FIGS. 5 and 6).

The photosensitive paper feed roller 22 normally remains stationary inspite of the rotation of the drive mechanism and is associated with thatdrive mechanism through a clutch so that it is intermittently driven bymeans of cam, microswitch and the like so as to feed paper sheets one byone at suitable time intervals. In the illustrated embodiment, a geartrain 44 associated with the paper transport roller 24 is controlled byan electromagnet 45 to transmit the drive to the rollers 23, which thusrotate the paper feed roller 22. A microswitch 46 provided between thetransport rollers 23 and the electrically charging means 27 is normallyopen to maintain the electromagnet inoperative, whereby the rollers 23are operatively associated with the rollers 24 via gear train 44 tothereby cause the paper feed roller 22 to feed a paper sheet from thepaper supply table 21. The paper sheet thus fed is passed by thetransport rollers 23 to close the microswitch 46, whereby theelectromagnet 45 is energized to attract the gear train 44 so that thegear train 44 is disengaged from the gear 24, of the roller 24 tothereby disconnect the transmission between the rollers 23 and 24. As aresult, the paper transport rollers 23 and feed roller 22 are stoppedand accordingly the paper sheet P is stopped from moving.

A duct 47 for the drier means 32 is provided in the space between theunderside of the paper supply table 21 and the L-shaped optical system.As shown in FIG.

3, the duct 47 has a bifurcated end portion forming two branch ducts 47,and 47 which extend outwardly of the opposite sides of the opticalsystem so as to introduce warm air to the oppositesides of the driermeans. Thus, the interior construction of the housing can be madecompact without obstructing the light path of the optical system, andaccordingly the entire apparatus can be made compact as well.

The blower 20 sucks the warm air around the light source 17 and over theoptical system, and the sucked warm air is suitably heated by the heater33 and blown against the developed photosensitive paper to dry the sameand fix a formed image thereon. Therefore, even if the temperature riseof the air within the machine housing resulting from the heat energyemitted from the light source 17 is minimized or if the illuminatingstation is closely adjacent to the photosensitive paper supply station,no variation will be caused in the resistance characteristic of thephotosensitive paper by temperature while the radiant heat energy fromthe light source may be utilized to dry the wet photosensitive paper tothereby economize the wattage of the heater 33. A cooling fan 18 isprovided adjacent to the light source 17 to cool the same.

Another example of the photosensitive paper transport means will bedescribed with reference to FIG. 4. Especially to make theelectrophotographic copying apparatus compact in structure, thisalternative example of the photosensitive paper transport means isarranged so that the distance of travel a of the original to be copiedand the distance of travel b of the photosensitive paper are in therelation that a b or a b (FIG. 2) and that the arrival of the originalat the illuminating station occurs concurrently with the arrival of thephotosensitive paper at the exposure station. As seen in FIG. 4, anendless drive transmission chain 38 is disposed on a gear 37 secured tothe housing 1 so as to transmit the drive of motor 36 via gear 37 togears 39 and 24 carried on rollers 39 and 24,, respectively. A furthergear 41 secured to the housing of the original transport means 5 isassociated with the gear 39 via interconnecting gear 40. A first set oforiginal transport rollers 8 carrying a gear 8' thereon and a second setof original transport rollers 9 carrying a gear 9' thereon are providedso that the gear 8' and 9 engage the gear 41. The second set of rollers9 is followed by third and fourth sets of rollers 10 and 11. The thirdset of rollers 10 is connected with the second roller set 9 via aninterconnecting gear 10 and the fourth set of rollers 11 is connectedwith the third roller set 10 via an interconnecting gear 43. Thus, thereis provided a unitary drive system for the photosensitive paper and theoriginal.

In the described drive system, if the gear ratio between gears 8' and 9is 2 l, the peripheral velocity of the first roller set 8 will be halfthat of the second roller set 9, so that the distance of travel a of theoriginal and the distance of travel b of the photosensitive paper are inthe relation that a b. As shown in FIG. 2, the gear 24 is associatedwith a gear train 44 mounted on a rockable arm 90 so that a set ofphotosensitive paper transport rollers may be driven through gear train44. The set of rollers 23 is rotated at a velocity double that of thefirst roller set 8 but equal to that of the second roller set 9. Anelectromagnet 45 disposed adjacent to the rockable arm 90 is controlledby microswitch 46 provided just behind the first roller set 8 and justbefore the electrically charging means 27. A plunger 91 is ex tendedinwardly from the rockable arm 90 in opposed relationship with theelectromagnet 45.

In operation, when an unshown power switch is closed the motor 36 startsto drive the chain 38, which in turn drives the photosensitive paperfeed roller 22 via gear train 44 and rollers 23, whereby an uppermostpaper sheet P is fed from the supply table 21. When the paper sheet P isabout to reach the electrically charging means 27, the leading edge ofthe paper sheet actuates the microswitch 46 to energize theelectromagnet 45, which thus attracts the plunger 91 and accordinglyrocks the rockable arm 90 to thereby disconnect the transmission of thedrive from the drive source to the rollers 23, whereby the paper sheet Pis stopped before it enters the electrically charging means 27.

Subsequently, when an original to be copied is nipped between the firstset of transport rollers 8, the leading edge of the original actuatesthe microswitch 92 to open the circuit of the electromagnet 45, which isthus deenergized to release the plunger 91 and return the rockable arm90 to its initial position. Thus, the

drive transmission is restored to drive the rollers 23 via gear train 44so as to move the paper sheet P again.

The paper sheet P is moved by the rollers 23 whose peripheral velocityis double that of the first set of original transport rollers 8. In thisway, the original and the paper sheet travel different distances atdifferent velocities but they reach the original illuminating station 4and the through-slit exposure means 28, respectively, at the same time.Thereafter, the original is transported into the illuminating station 4through the second set of transport rollers 9 driven at the samevelocity as the paper transport rollers 23, and further passed throughthe third and fourth sets of transport rollers 10 and 11 for dischargeonto the original receiving tray 16. On the other hand, the paper sheetP now in the exposure means 28 is exposed to light through the opticalsystem 7 so that the optical image of the original is formed on theexposed surface of the paper sheet P, which is thereafter passed to thedeveloping means 29 and then to the fixing means 32, and finallydischarged out of the copying apparatus.

In the above-described process, the velocity at which the original ismoved by the first set of rollers 8 is lower than the velocity at whichthe paper sheet is transported, but after nipped between the second setof rollers 9 the original is transported at the same velocity as thepaper sheet. Such change in the velocity of the original causes agreater tension in the original which might break or injure the materialof the original. To eliminate such a possible inconvenience, a one-waytransmission clutch mechanism as shown in FIGS. 5 and 6 is providedbetween the shaft 93 of the first roller set 8 and the gear 8' so thatthe first roller set 8 may be accommodated to the velocity of the secondroller set 9.

In the operation of the one-way clutch mechanism as viewed in FIG. 6,rotation of the gear 8' drives the notched cam 98 by means of theinterconnecting pin 102 which is received in the opening 97 in the gear8. Thus, when the gear 8' rotates clockwise, the rollers 100, which areurged outwardly by the springs 101, become wedged between the clutch 96and the reduced areas of the notches in the cam 98, so that clockwiserotation is imparted to the shaft 93. However, when the advancingvelocity of the original is increased, the roller 8 causes the shaft todrive the clutch 96, thereby overcoming the wedging action andpermitting free wheeling rotation of the roller 8.

With the described alternative form of the drive system, the distance aover which the original travels after it has actuated the microswitch 92but before it enters the illuminating station 4 and the distance b overwhich the paper sheet P is moved in response to a signal provided bythat actuated microswitch 92 before it enters the exposure means 28 canbe selected in the relation that a b or a b as described. Thus, theelectrophotographic copying apparatus incorporating such drive systemmay be easier to design and this is very helpful to make the entireapparatus compact.

Also, if the peripheral velocity of the first set of original transportrollers 8 is lower than the other transport rollers as in the shownexample, the original which may be curled or thin before fed isprevented from being wrinkled or otherwise deformed by the firsttransport rollers or from being nipped by these rollers obliquelythereto, whereby the original may be free of any undesirable injury.This is also very useful to achieve a highspeed copying operation.

Referring to FIGS. 7 and 8, there is shown an example of means forfeeding paper sheets. Paper sheets P piled on the paper supply table 21are fed in succession from the uppermost one to the lower by a paperfeed roller 22 while being separated from the remaining paper sheets bya separator pawl 94, and a first separated paper sheet P, is guidedalong a guide 48 into the nip between paper transport rollers 23 and23,. The paper sheet thus nipped is advanced until the leading edgethereof enters a passage 95 and actuates the lever 46, of themicroswitch 46 to stop a paper feed drive motor M. Thus, the paper sheetP, is stopped temporarily. When the motor M is again started by asubsequent start signal, the paper sheet P, is further advanced to asubsequent station such as electrically charging means or image transferstation.

After the trailing edge of the first paper sheet P, has passed themicroswitch 46, a second paper sheet P is advanced until its leadingedge comes to the front of the microswitch 46 and waits for the nextstart signal.

In order to accomplish such intermittent feed of paper sheets, the feedof the second paper sheet P occurs after the trailing edge of the firstpaper sheet P, has passed the feed roller 22. If the velocity of thefirst paper sheet P, as it passes through the transport rollers 23 and23, is equal to or higher than the velocity of the second paper sheet Pas it is fed by the feed roller 22, these two paper sheets P, and P, wilbe moved while over-lapping each other over a length C as shown in FIG.8. Therefore, the switch 46 can no longer detect the leading edge of thesecond paper sheet P, and this is also the case with all the succeedingpaper sheets. Thus, feed of paper sheets would be continued until thepaper sheet stock exhausts on the supply table 21.

To prevent this, the prior art arrangement has been such that theperipheral velocity of the feed roller 22 is lower than that of thetransport rollers 23 and 23, and by utilizing the velocity differencethe second paper sheet P is fed between the rollers 23 and 23, onlyafter the trailing edge of the first paper sheet P, has passed theserollers.

Such an arrangement, however, has entailed the requirement that thedistance B be relatively great or the distance C be relatively small orthat an extremely great difference be provided between the peripheralvelocity of the roller 22 and that of the roller 23. However, when theseparator pawl 94 is employed to ensure the separation of each papersheet, the distances B and C must be so great that it is difficult toaccomplish such a design as will satisfy the foregoing requirement. Itis also undesirable in designing that an extremely great velocitydifference is provided between the rollers 22 and 23.

In the example of the paper sheet feeding means now under discussion, anarm 50 is provided to interconnect the paper feed roller 22 and thepaper transport roller 23, a sprocket 22, is securely mounted on theshaft of the feed roller 22, and a sprocket 51 is loosely mounted on theshaft 23' of the transport roller 23, the sprocket 22, having a greaterdiameter than the sprocket 51 so as to provide a great velocitydifference. A chain 52 is entrained on the two sprockets 22, and 51 toestablish an operative association therebetween. The roller 23, disposedadjacent to the transport roller 23 is driven by the motor M and adaptedto be urged into contact with the roller 23. Loosely mounted on theshaft 23 of the transport roller 23 is a floating ring 53 in sideby-siderelationship with the sprocket 51, and between the sprocket 51 and thering 53 there is interposed a windup spring clutch 54 or other suitableone way transmission clutch. The transport roller 23 has a pin or otherengaging member 55 at one end face thereof, and the floating ring 53 isformed with an engaging member 56 cooperating with the engaging member55 on the transport roller 23, as shown in FIG. 10.

When the motor M is started by a start signal and the rollers 23, and 23are thereby driven to rotate, the following processes occur insuccession;

1. The engaging member 55 of the transport roller 23 is displaced to theposition of FIG. 11 and strikes and pushes the shoulder 56, of theengaging member 56 of the floating ring 53.

2. Thus, the floating ring 53 is rotated together with the transportroller 23, to thereby drive. the sprocket 51 via wind-up spring 54.

3. The drive is transmitted from the sprocket 51 through the chain 52and sprocket 22, to the paper feed roller 22, which is thus rotated tofeed an uppermost paper sheet P, from the supply table 21 with the aidof the separator pawl 94.

4. The paper sheet P, passes between the rollers 23 and 23, and itsleading edge actuates the actuator lever 46, of the stop microswitch 46,which is thereby opened to stop the motor M and accordingly the papersheet P, is stopped at its predetermined stop position.

5. By the next start signal the motor M is again started to advance thepaper sheet P, from the stop position, whereupon the paper feed roller22 is also driven to rotate.

6. At this point of time, however, the trailing edge of the paper sheetP, is still engaged by the feed roller 22, so that the rotation of therollers 23 and 23, is transmitted through the drawn paper sheet P, tothe feed roller 22, which is thus rotated at the same velocity asrollers 23 and 23,, whereby the smallerdiametered sprocket 51 is nowdriven by the greater-diametered sprocket 22, through the chain 52.

7. Because of the diameter difference between the two sprockets 22, and51, the smaller sprocket S1 is rotated faster than the sprocket 22, andaccordingly the engaging member 56 is rotated faster than the engagingmember 55 of the transport roller 23, whereby the engaging member 56pushes the engaging member 55 into the position of FIG. 10 at leastuntil the trailing edge of the paper sheet P, leaves the feed roller 22.

8. Since engaging member 55 is integral with the transport roller 23,the floating ring 53 does not follow the movement of the sprocket 51 andthe wind-up spring 54 is loosened, so that the floating ring 53 iscaused to slip.

9. The paper feed roller 22 is being driven by the paper sheet P, movedby the transport roller 23, as described above, and therefore, when thetrailing edge of the paper sheet P, leaves the feed roller 22, thesprocket 22, stops its rotation to thereby stop the first paper feedingoperation and the engaging member 56, while the transport roller 23 andengaging member 55 thereon continue to rotate.

10. When the transport roller makes substantially one rotation, theengaging member 55 again actuates the engaging member 56 to therebyresume the paper feed to feed a second paper sheet P 11. The first papersheet P is still advancing and its trailing edge passes between therollers 23 and 23 whereafter the leading edge of the second paper sheetP is in turn nipped between the rollers 23 and 23 After the trailingedge of the first paper sheet P has passed the stop switch 46, theleading edge of the second paper sheet P actuates that switch to stopthe motor M and the second paper feeding operation.

In the stages mentioned under items 6) and 7) above, when the sprocket51 is rotated faster than the roller 23, the wind-up spring 54 isloosened and the force acting on the floating ring 53 becomes too smallto drive that ring. Therefore, the force of the spring 54 may be set soas to enable the floating ring 53 to be driven thereby.

According to the present invention, when the first paper sheet l isadvanced until its trailing edge leaves the paper feed roller 22, thisroller temporarily stops its rotation until the first paper sheet Pcompletely passes through the transport rollers 23 and 23 andimmediately after such passage of the paper sheet P the leading edge ofthe second paper sheet P reaches the transport rollers 23 and 23Therefore, no possibility arises that the first and second paper sheetsP and P overlap each other to cause continuous feed of these papersheets. Moreover, a cycle of operation from the paper feed through thetemporary stoppage till the resumption of the paper feed is accomplishedautomatically by a simple mechanism, and thus malfunctioning can beminimized and highly reliable performance is ensured.

Referring to FIGS. 12 to 17, there is shown another example of theoriginal transport means for the electrophotographic copying apparatusaccording to the present invention. This alternative embodiment isintended to ensure any thin or thick original to be transported at auniform velocity without jamming in the course of transport, to preventthe original from being injured or jamming as a result of excessivelygreat contact pressure between the original and the transport means, and

ensure timing between the feed of the original and that of a paper sheetif the copying apparatus is of the type in which a signal for feeding apaper sheet is detected by utilizing a predetermined velocity of theoriginal passing through the original transport means.

In FIGS. 12 to 17, there are seen groups of originals transport rollersdisposed before and behind the original illuminating station. Lowerrollers 57, 59, 62 and 63 of these roller groups are journaled to themachine housing 1 or to opposite bearing plates 66 integral with themachine housing (only one of such bearing plates being shown in FIG.12). Upper rollers 8, 9, 10 and 11 are journalled to opposite bearingplates 61 integral with upper guides 58, 66, 67 and 64 so as to form andupper roller group supporting unit which is separate from the machinehousing 1. Such upper roller group supporting unit is detachably mountedfor vertical movement and slight pivotal movement with respect to thehousing 1, and at least the two endmost rollers 8 and l 1 are mountedfor vertical movement with respect to the bearing plates 61. Thus, theupper and lower rollers forming each set are brought into contact witheach other when the original is fed therebetween.

In the shown example, the vertical movement of the above-described upperroller group supporting unit may be accomplished by springs 72 and 72secured to spring securing means 70 provided at the opposite ends of thefixed bearing plates and to spring securing means 71 provided in thebearing plates 61 of the upper roller group supporting unit,respectively. These springs 72 and 72 bias the upper roller groupsupporting unit downwardly so as to bring the upper rollers 9 and 10into contact with the corresponding lower rollers 59 and 62. At the sametime, the other upper rollers 8 and 11 are lowered by their own gravityinto contact with the corresponding lower rollers 57 and 63.

When a thick original G, having been set in position, is fed towardguides 58 and 58 in the direction indicated by arrow in FIG. 16-1, theguide 58 is raised by the original to a degree corresponding to thethickness thereof against the force of spring 72,. This causes theroller bearing plates 61 to pivot about the point of contact between therollers 62 and 10. Further, the original G is to be manually'forcedbetween the rollers 57 and 8 as shown in FIG. 16l, whereas the roller 8is lowered by its own gravity into contact with the roller 57 becausethe roller 8 is movable vertically with respect to the bearing plates61, which are already displaced clockwise. Therefore, at the moment whenthe original G begins to be nipped between the rollers 57 and 8, theroller 8 is lightly raised to contact the bearing plates 61, and at afurther moment when the original is completely nipped between theserollers 57 and 8, the roller 8 is raised to a degree corresponding tothe thickness of the original and the forward portions of the bearingplates are now raised by the roller 8. It will thus be noted that thecontact pressure between the rollers 57 and 8 is very low at the momentwhen the original is nipped therebetween and once nipped, the originalis transported without slipping with the aid of the force of spring 72,,whereby no forcible pressure may occur in the original as it is nippedand the original may be free of injury or deformation.

The original G is further transported to guides 65 and 66 by rollers 57and 8 as shown in FIG. 16-2. Since the bearing plates 61 are alreadyraised as described, the guide 66 fixed thereto is also raised and thusa greater spacing is provided between the guide 66 and the guide 65. Inthe position of FIG. 13 where no original is fed as yet, the rollers 57and 8 are in contact with each other and the guides 65 and 66 aresuitably spaced apart, and once the original is nipped between therollers 57 and 8, the guides 65 and 66 are spaced apart a greaterdistance than before. Such a greater spacing between the guides 65 and66 ensures smooth passage of the original therebetween without jammingor friction relative to the guides which may result in the irregularvelocity of movement of the original. The leading edge of the originalas it passes the vicinity of the guides 65 and 66 is detected as bymicroswitch 92 (FIG. 1) and, in accordance with the detection signal,the feed of a paper sheet is started so that it is subjected to theexposure process exactly in synchronism with the movement of theoriginal without any timing error. Thereafter, the leading edge of theoriginal reaches the rollers 59 and 9, which are then ready to nip theoriginal therebetween as shown in FIG. 16-2 because the roller 9 israised by the forward portion of each bearing plate 61 which has beenraised since the original was nipped between the preceding rollers 57and 8. Thus, the original is allowed to be smoothly nipped between therollers 59 and 9.

The original is to be further transported to the illuminating station.When the leading edge of the original is nipped between the rollers 59and 9, the roller bearing plates 61 are urged to swing clockwise aboutthe point of contact between the rollers 59 and 9 by the springs 72, inthe forward portions of the bearing plates 61, so that a spacingcorresponding to the thickness of the original is provided between therollers and 62. In other words, the forces of the springs 72, and 72provided at the opposite ends of the bearing plates 61 are so presetthat the upper roller group supporting unit becomes parallel to thelower roller group supporting unit at that time, as shown in FIG. 16-4.

Thus, the spacing between the guide 67 and the glass sheet 4 is madeslightly greater than the thickness of the original so as to allow theoriginal to pass smoothly through the illuminating station at a constantvelocity without jamming or making frictional contact with the guide 67,whereby proper exposure process is ensured.

If the rollers 62 and 10 of the subsequent set are in contact with eachother when the leading edge of the original reaches these rollers, as isthe case with the copying apparatus of the prior art, then a time delaywill be unavoidably caused before the original is nipped between therollers. According to the present invention, the rollers 62 and 10 arespaced apart a distance substantially corresponding to the thickness ofthe original as described already, so that such time delay can beminimized at this point of time to enable proper passage of the originalthrough the illuminating station. During that time, the roller 11 islowered by its own gravity to contact the roller 63 to thereby shieldthe illuminating station from any extraneous light. Also, even if thetrailing edge of the original completely leaves the rollers 57 and 8while the original is passing through the illuminating station, it willin no way affect the transportation of the original because the upperroller group supporting unit as a whole makes no movement except theroller 8 which is lowered by its own gravity to contact the roller 57.When the leading edge of the original further reaches the rollers 63 and11, the roller 11 is raised by that leading edge to a degreecorresponding to the thickness of the original and assumes a position asshown in FIG. 16-5. Guides 64 and 64 interposed between the sets ofrollers 62, 10 and 63, 11 are spaced apart a sufficient distance toallow the smooth passage of the original therebetween. When the originalis further transported by the rollers 63 and 11 and its trailing edgecompletely leaves the rollers 59 and 9 as shown in FIG. 16-6, the upperroller group supporting unit is swung counter-clockwise about the pointof contact between the rollers 57 and 8 by the spring 72,, whereby theoriginal continues to be transported smoothly.

As has been noted above, any original having a great or small thicknesscan be transported smoothly at a uniform velocity so that clear copiescan be obtained. Even if the original should be jammed somewhere in thecourse of transport, the original may be readily removed by dismountingor raising the detachable upper roller group supporting unit. This isaccomplished by the arrangement described hereunder.

In FIG. 15, the upper roller group supporting unit 75 is mounted forpivotal movement about a shaft 85 provided on the side plate 76 of thatunit. An upper lid 77 has dependent plates 78 secured thereto, and adowel 79 is secured to each dependent plate 78 by means of spring 80.Thus, the upper roller group supporting unit can be raised by raising oropening the upper lid 77.

When the upper roller group supporting unit is in closed position, ahook 81 extending downwardly from the upper lid 77 engages a dowel 83provided at the upper end of a lever arm 82, whereby springs 80 and 84are compressed to maintain the lid 77 closed.

When it is desired to open the upper lid 77, the lever arm 82, which isnormally biased in one direction by a spring 86, may be gripped andraised to release the engagement between the dowel 83 of the lever 82and the book 81 of the upper lid 77.

According to the above-described embodiment, the original transportrollers and guides are divided into upper and lower groups with the pathof original interposed therebetween, and this provides a ready access tothe interior of the original transport means so as to eliminate jammingof the original in its path or clean the illuminating station,especially the glass sheet in that station.

What is claimed is:

1. An electrophotographic copying apparatus comprising a housing havingan exposure station and an original illuminating station, originalfeeding means for transporting an original through the originalilluminating station, paper sheet supply means, means for generating apaper sheet supply signal, a paper feed drive motor energized by saidsignal, a transmission system driven by said motor, a paper feed rollerand paper transport rollers driven by said transmission system todeliver paper sheets successively from said supply means to the exposurestation, means connected to said motor and including a switch actuatedby the leading edge of each paper sheet at a predetermined position forsuccessively stopping the paper sheets at a position disposed betweenthe paper sheet supply means and the exposure station until generationof a said supply signal, wherein said switch is disposed between one ofsaid transport rollers and said exposure station, said transmissionsystem including transmission mechanism means for temporarily stoppingmovement of said paper feed roller upon movement of a trailing edge ofeach paper sheet past said feed roller and for resuming movement of saidfeed roller during a period of continuous movement of said transportrollers thereby providing a space between succeeding sheets of paper,and L-shaped optical system means for optically connecting said originalilluminating station to an exposure station so that each of said papersheets is exposed to light carrying the image of said original.

2. An apparatus according to claim 1, wherein said transmissionmechanism means for temporarily stopping said paper feed roller includesfloating ring means having a first engaging member and being rotatablymounted on one of said paper transport rollers, a second engaging memberfixed to said one transport roller, a first sprocket, wind-up springclutch means connected between said first sprocket and said floatingring means, a second sprocket fixed to said paper feed roller, a chaininterconnecting said first and second sprockets, whereby when thetrailing edge of each paper sheet leaves said paper feed roller, saidsecond sprocket and said first engaging member of said floating ringmeans are temporarily stopped while said paper transport roller and saidsecond engaging member continue to rotate so that a preceding papersheet is separated from a succeeding paper sheet.

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1. An electrophotographic copying apparatus comprising a housing havingan exposure station and an original illuminating station, originalfeeding means for transporting an original through the originalilluminating station, paper sheet supply means, means for generating apaper sheet supply signal, a paper feed drive motor energized by saidsignal, a transmission system driven by said motor, a paper feed rollerand paper transport rollers driven by said transmission system todeliver paper sheets successively from said supply means to the exposurestation, means connected to said motor and including a switch actuatedby the leading edge of each paper sheet at a predetermined position forsuccessively stopping the paper sheets at a position disposed betweenthe paper sheet supply means and the exposure station until generationof a said supply signal, wherein said switch is disposed between one ofsaid transport rollers and said exposure station, said transmissionsystem including transmission mechanism means for temporarily stoppingmovement of said paper feed roller upon movement of a trailing edge ofeach paper sheet past said feed roller and for resuming movement of saidfeed roller during a period of continuous movement of said transportrollers thereby providing a space between succeeding sheets of paper,and L-shaped optical system means for optically connecting said originalilluminating station to an exposure station so that each of said papersheets is exposed to light carrying the image of said original.
 2. Anapparatus according to claim 1, wherein said transmission mechanismmeans for temporarily stopping said paper feed roller includes floatingring means having a first engaging member and being rotatably mounted onone of said paper transport rollers, a second engaging member fixed tosaid one transport roller, a first sprocket, wind-up spring clutch meansconnected between said first sprocket and said floating ring means, asecond sprocket fixed to said paper feed roller, a chain interconnectingsaid first and second sprockets, whereby when the trailing edge of eachpaper sheet leaves said paper feed roller, said second sprocket and saidfirst engaging member of said floating ring means are temporarilystopped while said paper transport roller and said second engagingmember continue to rotate so that a preceding paper sheet is separatedfrom a succeeding paper sheet.